Sediment samples from the Romanian sector of the Danube River and the Black Sea coast were analyzed for Pu and Am. Three different
ways of bringing the samples into solution were tested: acid attack, microwave digestion and alkaline fusion. A conventional
anion-exchange resin was used to separate plutonium from other radionuclides and several variants were tried to improve the
separation of americium. The preparation of thin sources for alpha-spectrometry was tested through electrodeposition and coprecipitation
with Nd(III). Discussion and recommendations for the dissolution step, the americium separation and preparation of alpha sources
The possibility to obtain new information about the U/Th contamination using the patterns of the fission track micromapping is put into evidence. For the investigated samples, bed load sediments sampled from Danube river and Delta, fission track micromappings were obtained using the neutron-induced fission of the U and Th elements and the track registration of their fission fragments in muscovite track detectors. Utilising the optical microscopy, these micromappings were used both for U and Th content measurements and for studies of U/Th atom distributions. Considering the track micromapping pattern as a characteristic of the U/Th atom distribution in the analysed sample, and basing on the micromapping patterns that were previously obtained for the samples contaminated in the specific conditions, the authors were able to establish: (1) the presence of the contamination of the sediments in spite of the fact that the U/Th concentration values did not exceed the natural background values, (2) the solubility of the U/Th chemical compounds in the initial waste and (3) the presence of a succession of U/Th contaminations as well as the presence of the transported contamination.
The concentration distributions of U and Th nuclides in some sediment and algae samples from the Romanian sector of the Danube river and the Black Sea coast are presented. Data are obtained by neutron-induced fission activation analysis, epithermal instrumental neutron activation analysis and radiochemical separation using tracers followed by -spectrometry counting of stainless steel discs after electrodeposition. The analysing time, the working steps, the necessary equipment, the information and quality of the obtained results are discussed.